Composition for tracer unit



March 21, 1961 R. H. HEISKELL 2,976,136

COMPOSITION FOR TRACER UNIT Original Filed June 29 1948 {1- WATERPROOF VPAINT IGNITER COMPOSITION INVENTOR. R. H. HEISKELL 2,976,136 PatentedMar. 21, 1961 COMPOSITION FOR TRACER UNIT Raymond H. Heiskell, 517 S.Alameda Blvd, Compton, Calif.

Original application June 29, 1948, Ser. No. 35,960, now Patent No.2,899,291, dated Aug. 11, 1959. Divided and this application Feb. 10,1959, Ser. No. 795,310

2 Claims. (Cl. 52-2) (Granted under Title 35, US. Code (1952), see. 266)This invention relates to a tracer ammunition unit especially adaptedfor use in 20 mm. projectile and more particularly, it concerns thecombination of an improved sensitive tracer composition, and a slowburning nonflash igniter composition therefor.

This application is a division of my copending application Serial No.35,960, filed June 29, 1948, now US. Patent No. 2,899,291, issued August11, 1959.

Heretofore tracer ammunition used by' our Armed Forces provedunsatisfactory especially when used in night encounters, in that, underconditions of darkness the flash therefrom upon ignition of the tracercomposition by the igniter composition caused excessive flash and toomuch light streak at the muzzle of the gun, thus illuminating anddisclosing the position of the gun to the enemy and confusing andmisleading the gunner or fire director when aiming at the gun isaccomplished by observation of the tracer streak. Such tracer ammunitionalso proved not altogether satisfactory when used in day encountersinasmuch as when the tracer composition was ignited the tracer streakemitted therefrom was of insufiicient intensity to permit the firedirector to follow the tracer streak as the projectile traveled along atrajectory.

The present invention is especially adapted to obviate the abovementioned flash and bright streak of light occurring at the gun muzzleas the projectile is fired therefrom, and also producing a tracer streakof sufiicient intensity to permit the gunner or fire director to observethe tracer streak and follow the flight of the projectile either atnight or during the day.

Accordingly, it is an object of the invention to provide a compositionfor a .tracer unit for a projectile comprising a new and improved lightemitting trace composition including a slow burning non-flash ignitercomposition therefor.

Another object is to provide a new and improved igniter composition fora tracer unit for a projectile adapted to delay ignition of a new andimproved tracer composition for a predetermined period of time after theprojectile has been fired from a gun and traveled a substantial distancefrom the muzzle thereof and in which the tracer composition, whenignited by the igniter composition, produces a tracer streak ofsufficiently bright intensity to permit the gunner to follow the flightof the projectile either at night or during the day as the projectiletravels along a trajectory.

Other objects and advantages of the present invention will become moreapparent during the course of the following description taken inconnection with the accompanying drawing.

In accordance with the present invention the new and improved slowburning non-flash or dark igniter composition for the tracer unit iscomposed of a mixture of barium peroxide, antimony sulfide, magnesium,and a Inbricant of graphite, and a sensitive light emitting tracercomposition composed of a mixture of magnesium, strontium nitrate,strontium tartrate, hexachlorobenzene, charcoal, and a binder of stearicacid.

Referring to the drawing, each of the aforesaid mixtures is mixedseparately and pressed or moulded into pellet form thereby to form aslow burning non-flash igniter composition pellet and a sensitive lightemitting tracer composition pellet, the tracer unit being completed bypressing the igniter pellet onto the tracer pellet and thereaftercoating the entire tracer-igniter unit with a moistureproof paint such,for example, as waterproof paint of the type known to those skilled inthe art as Bakelite Varnish No. XV-1657.

The igniter composition of the present invention may be obtained bymoulding a mixture of the following ingredients, the ingredients beingproportioned by percentage by weight such, for example, as 7678.4%barium peroxide, ISA-23% antimony sulfide, 0-2.2% magnesium, and .1-1%of graphite. In preparing the ingredients of the igniter composition ithas been found that the best results are obtained when the bariumperoxide, antimony sulfide, and magnesium are of such proportions as topass through a US. standard sieve, mesh size 200 and the graphite is ofsuch proportion as to pass through a US. standard sieve, mesh size 325.

Now, the nature and purpose of the igniter unit of the present inventionhaving been indicated in a general way, the following specific exampleof the igniter composition thereof is illustrated together with the meshsize of the sieve used. In this example the ingredients of the ignitercomposition are given in percentages by weight.

Slow burning non-flash igniter composition The tracer composition of thepresent invention may be obtained by moulding a mixture of the followingingredients, the ingredients being proportioned by percentage by weightsuch, for example, as 31.838% magnesium, 30.9-38% strontium nitrate,1227.3% strontium tartrate, 4.6-5 hexachlorobenzene, 2O.9% charcoal, and4.54% stearic acid. In preparing the ingredients of the tracercomposition, it has been found that the best results are obtained whenall the ingredients comprising the tracer composition are of suchproportions as to pass through a U8. standard sieve, mesh size 100.

Now, the nature and purpose of the tracer unit of the present inventionhaving been indicated in a general way, the following specific exampleof the tracer composition thereof is illustrated together with the meshsize of the sieve used.

Sensitive light-emitting tracer composition for both daylight and nightuse, a small percentage of hexachlorobenzene was added to the tracermixture to improve this color effect of the trace streak and it was alsofound that by .the addition of a small amount of pulverized charcoal tothe tracer composition the ignition thereof was improved, as theaddition of the charcoal when mixed with the other fine powderingredients of a c M! the tracercomposition in the aforesaid proportionsdecreased the compressibility of the entire mixture, thus making it moreporous and improving the ignition thereof.

In preparing the igniter composition it was found that when the bariumperoxide, antimony sulfide, and magnesium were mixed with the graphitein the aforesaid proportions, the ignition sensitivity characteristicsthereof proved entirely satisfactory and the combustion thereof wassufficiently retarded to ignite the tracer composition in predeterminedtime delayed relation with respect to ignition of the ignitercomposition. It was also found that by maintaining the particle size ofthe antimony sulfide smaller than 200 mesh size, the frictionalsensitivity of the particles of which the igniter composition iscomposed is sufiiciently low to prevent premature detonation of themixture. Furthermore, proper functioning of the,

tracer unit is obtained when the tracer unit is loaded into the tracercavity arranged in the projectile with a serrated ram at .a pressure,such, for example, as from 30,000 46,000 p.s.i.

From the foregoing description it will be understood that a compositionfor a. tracer unit for a projectile has been compounded and constructedin which the igniter composition thereof is adapted to delay ignition ofthe light emitting tracer composition thereof for a predetermined periodof time after ignition of the igniter composition as the projectile isfired from a gun whereby ignition of the tracer composition will occur asubstantial distance from the muzzle of the gun such, for example, asfrom 75 to 125 yards, thereby preventing area illumination of thebattery, and also preventing the flash upon ignition of the tracecomposition from producing a blinding effect on the gunner.

Furthermore, the present invention is adapted to improve the daylightvisibility of the tracer streak emitted from thetracer composition, suchtracer streak being sufficiently bright to permit the gunner to observeand fol-.

low the streak as the projectile travels along a trajectory.

From the foregoing description it will be understood that ignition ofthe tracer composition by the igniter composition and the appearanceof-the tracer streak therefrom will not occur until a predeterminedperiod of time has elapsed after ignition'of the igniter composition.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

7 The invention herein described and claimed may be manufactured andused by or for the Government of the United States of America forgovernmental purposes without the payment of any royalties thereon ortherefor.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A slow-burning, non-flash igniter mixture for a tracer unitconsisting essentially of 76 to 78.4% barium peroxide, from 18.4 to 23%antimony sulphide, up to 2.2% magnesium, and containing an amount up to1% graphite.

' 2. A slow-burning, non-flash igniter composition for a tracer unitconsisting essentially of 76 to 78.4% barium peroxide, from 18.4 to 23%antimony sulphide, and up to 2.2% magnesium.

References Cited in the file of this patent UNITED STATES PATENTS2,115,047 Stevenson et a1 Apr. 26, 1938 2,362,502 Schladt Nov. 14, 19442,410,801 Audrieth Nov. 12, 1946 2,726,943 I Heiskell Dec. 13, 1955 2,899,291 Heiskell Aug 11, 1959 FOREIGN PATENTS 7,562 Great Britain Feb.4, 1899 349,839 Great Britain June 4, 1 931

1. A SLOW-BURNING, NON-FLASH IGNITER MIXTURE FOR A TRACER UNITCONSISTING ESSENTIALLY OF 76 TO 78.4% BARIUM PEROXIDE, FROM 18.4 TO 23%ANTIMONY SULPHIDE, UP TO 2.2% MAGNESIUM, AND CONTAINING AN AMOUNT UP TO1% GRAPHITE.